This invention relates to data communications systems, and more particularly, to a data broadcast system which uses a hierarchical file system for organizing data broadcast from a network of servers to a client.
Referring to FIG. 1, a broadcast data communications system 100 includes a network of servers and clients. A first server 102 and a second server 104 are coupled to a first client 106 and a second client 108 via a broadcast delivery network 110.
Data is sent via broadcast from the servers 102 and 104 to the clients 106 and 108 on the one-way data delivery network 110 instead of via a two-way communications path, for the higher data capacity of a broadcast data delivery network. A two way communications path such as a telephone connection typically has data capacity of approximately 34 kilobits/second. A broadcast data network such as broadcast television, satellite, or cable television, on the other hand typically has data capacity of as high as 40 megabytes/second. Thus, the data capacity of a broadcast data network is 1200 times more than the data capacity of a two-way telephone connection.
In the prior art broadcast data communications system 100 of FIG. 1, respective data sent from a server to a client may be indexed independently by each server to inform the client of the respective data content. A client which receives data from a plurality of servers sorts through the respective data from each server to determine the data of interest to that client.
A server may include a respective index that is independent of the index of other servers or a server may not include any index. In addition, an index sent by a server in the prior art broadcast data communications system 100 may include only a simple linear index of the data content sent by that server. In any case, the client may be required to perform extensive data processing in determining the type and organization of data sent by each server in the prior art broadcast data communications system 100.
Accordingly, a primary object of the present invention is to provide a more sophisticated data indexing system for data broadcast from a plurality of servers in order to minimize data processing burdens on a client receiving such broadcast data. More particularly, a broadcast file system of the present invention organizes data from the plurality of servers into a hierarchical file system including a directory index.
In a general aspect of the present invention, a broadcast file system for delivering data from a plurality of servers to a client includes a broadcast delivery network coupled to the client for broadcasting the data to the client. Additionally, a broadcast file system server, coupled to the broadcast data network and the plurality of application servers, organizes the data available from the servers into a hierarchical file system having a directory index. Each of the plurality of servers registers with the broadcast file system server to send respective data under a respective directory within the directory index. A server access network couples the plurality of servers to the broadcast file system server.
The broadcast file system periodically broadcasts the directory index to the client via the broadcast delivery network. The client caches and provides this directory index to a client application. In this manner, the data available from the plurality of servers appears to the client application as a hierarchical file system of a computer operating system. Furthermore, the broadcast file system server periodically broadcasts the data available from the servers to the client via the broadcast delivery network such that the portion of the data requested by the client application from the directory index is available to the client application.
In another aspect of the present invention, the client requests specified data not available from the directory index via a two-way communications network. If the specified data is available from any of the plurality of servers, this specified data is sent to the client either via the two-way communications network or via the broadcast delivery network.
In a further aspect of the present invention, a database server coupled to the broadcast deliver network maintains a database. The respective data available from the database server includes tables from the database. The respective directory of the database server within the directory index organizes the tables according to a database schema. A client application specifies database schema parameters from the directory index when accessing data available from the database server.
These and other features and advantages of the present invention will be better understood by considering the following detailed description of the invention which is presented with the attached drawings.